A content delivery system that transmits content data representing content to user equipment is known. A system described in Patent Document 1 as one of such content delivery systems accepts content marker information transmitted by user equipment. Content marker information includes content identifier information for identifying content.
Then, the content delivery system stores the accepted content marker information. After that, in response to a content marker output request transmitted by the user equipment, the content delivery system transmits the stored content marker information to the user equipment.
On the other hand, upon reception of the content marker information, the user equipment prompts the user to select one of the received content marker information. Then, the user equipment transmits a content transmission request including the content marker information selected by the user to the content delivery system.
Upon reception of the content transmission request transmitted by the user equipment, the content delivery system transmits content data identified with the content transmission request to the user equipment. Consequently, without performing a cumbersome operation in order to specify content the user of the user equipment wants to view, the user can view the content.    [Patent Document 1] Japanese Unexamined Patent Application Publication No. JP-A 2004-173102
The content delivery system described above is configured to transmit the stored content marker information to user equipment in response to a request by any user. Therefore, the content delivery system has a problem that, even if one user wants only a specific user to see registered content marker information, a user other than the specific user may see the content marker information.